Dipole in an external electric field

AI Thread Summary
The discussion centers on the expression for torque on a dipole in an external electric field, questioning why it is represented as PxE instead of ExP. The key point raised is the significance of the order of the cross product in vector mathematics, where A x B yields a direction opposite to B x A. This difference is crucial in defining positive and negative directions for vector quantities, including torque and angular velocity. The conversation suggests that these definitions are rooted in the chosen coordinate system. Ultimately, understanding the vector properties and their implications is essential for accurately describing the torque on a dipole.
Prashasti
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Homework Statement


Why isn't the expression for torque on a dipole kept in an external electric field ExP? Why is it PxE?
No such indication has been given in any of the derivations, that it is mandatory for it to be PxE, so why can't it be ExP?

2. The attempt at a solution
Is it all about experiments?
 
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Prashasti said:

Homework Statement


Why isn't the expression for torque on a dipole kept in an external electric field ExP? Why is it PxE?
No such indication has been given in any of the derivations, that it is mandatory for it to be PxE, so why can't it be ExP?

2. The attempt at a solution
Is it all about experiments?
What's the essential difference in the cross products A x B versus B x A?
 
The direction of the resultant of A x B is just opposite to that of B x A...
 
Prashasti said:
The direction of the resultant of A x B is just opposite to that of B x A...
Right. So it comes down to the definitions of positive or negative directions for quantities in the chosen coordinate system. This includes assumed directions for positive or negative torques, angular velocities, etc., which are vector quantities (or pseudo vector quantities in some cases, but that's another topic).
 

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